Create stylised digital maquettes
Stefano Dubay shares his workflow for creating a free-form sculpture from concept to render
Turn an initial character concept into a free-form sculpture for feature animation in Zbrush
When you make a character maquette for feature animation from a concept, you need to capture the essence of what the designer intended. To do this, you have to observe the shape language the designer uses, because that’s the surest way to capture the true character in the drawing and bring it to life. I like to sculpt things in as free-form a way as possible.
First, I quickly flesh out the forms of the character – getting the main shapes of the face and body. The face is particularly important because that is where most of the character is, so be extra careful sculpting it and read the concept with care.
For the clothing and accessories, to keep the shapes clean, I use low-resolution meshes. That’s because the fewer polygons there are, the easier it is to avoid bumps and kinks. Instead of spending too much time polishing things, I use dynamic subdivision in Zbrush to tweak the shapes.
Once I’m happy with the overall shapes, it’s time to smooth them and, if needed, to locally sculpt details. I also use creasing to finely control the hardness of the edges.
Then it’s all in how you present your model. I like Renderman because it gives a lovely smooth final result and enables a lot of control in the final image.
01 STUDY THE SHAPES
First, I study the shapes of my concept, by Randy Bishop. Look at the silhouette’s curves – where they begin and where they end. Pay attention to how the curves behave. A curve isn’t usually weighted exactly in the centre. Look at where the curves change direction, and where they reach their apex.
02 BLOCK OUT THE FORMS
I create most of my parts in Zbrush, using a combination of Dynamesh and Zremesher, with some Zmodeler. I find that I can make most of my objects faster in Zbrush than in any other software.
In Zbrush, I start with a sphere, turn it in a Polymesh3d and Dynamesh it. This becomes my original ‘lump of clay’ that I can start working with.
03 SCULPT YOUR MODEL
To block in the forms, I like using the Move brush to get the rough shape. Another favourite brush is the Pinch brush. Pinch brush is a strange one because it has separate controls for elevation and for the amount it pinches the surface together (go to Brush> Modifiers>brushmodifiers). Establish the areas where the silhouette’s curves change direction abruptly using the Pinch brush with a high-value Brush Modifier. Try brushing the contours of the silhouette of your character and you’ll soon see how simple it is to break the curves.
Start simply, and then build up to complex. After roughly blocking in my model, I tend to break it up into parts. This way, I can work out the relationship between all of the different forms. By that, I mean that if I need to move an eyebrow a cheekbone or another feature, they are all broken up in parts, so I can handle them individually. Another benefit is that while tweaking the forms, I avoid messing up the surrounding areas. This way I can also keep the forms more easily and maintain the sharp transition of one form into another.
Cut your clay into pieces using the Slice Brush. This brush is asymmetrical, but in this case, you have no subdivision levels, so you can use Mirror and Weld to restore the symmetry.
Keep your Dynamesh as low as possible in all these steps (the same for Zremesh). Use Freeze Subdivision Levels instead if you want to keep sculpting, but you need to change the topology. You can add subdivisions to your mesh and still be able to Dynamesh if you use Freeze Subdivision Levels. It will delete the higher subdivision levels, but this is temporary. If you press it again, it will reproject the higher subdivision levels.
04 MAKE THE OTHER PARTS
I use Masking and Extract to generate the other parts now that I have finished building the foundation of my model.
I sometimes reweld all the separate parts to do this, but on a copy of my character’s model. I keep the rest separate until I’m ready to finalise the model.
Do the same thing for all of your character’s body, and then for the clothing and accessories.
For the body, keep in mind anatomy and use references and your concept. Even if a character is stylised, try to play with the shapes dictated by anatomy to suit and complement the design.
05 WELDING
Once all the basic blocks are in place, weld them together using Dynamesh. This is the one instance of my pipeline where I keep my Dynamesh resolution high because I want to avoid accidentally welding things together. Zremesh keeps things separate, but you cannot weld things together using it.
06 ZREMESHING
Now that you have welded your parts together with a highresolution Dynamesh, duplicate your subtool. Zremesh it as low as possible to have good geometry, subdivide it and reproject the details back on.
07 MAKE CLOTHING
First, mask the area of the T-shirt. Extract it, turn off Double – the thickness doesn’t matter because you can then delete everything but the inner polygroup.
Zremesh this surface and use Zmodeler to remove the unnecessary loops so you can straighten out the sleeve easily. Next, Zremesh the shirt again to even out the loops on the sleeve. Go to Zmodeler>faceactions>extrude to get your desired thickness. Don’t Smooth, use Dynamic Subdivision instead (on a mesh without subdivisions, hit [D]).
08 USE CREASING
To keep the edges that define the garment’s thickness from becoming soft when smoothing, you can either use support edges or creasing. But adding edges can cause problems if you accidentally smooth them later.
Creasing by default makes the edges razor sharp, but there are ways to control this by tweaking the Dynamic Subdivision >Smoothsubdivisionlvl and Crease >Creaselvl values for the piece.
Using this technique you can easily and finely control the hardness of the edges throughout the different accessories on the model, be they belts, straps or other items of clothing. Little details like these will really sell the model.
09 DECIMATION
To quickly move the model over to Maya and preserve the details without all the technical issues involved in making a model production ready, UV Map it and export with Displacement maps and so on. Decimate it and export the decimated mesh. As I have a heavily subdivided model, this means I preserve the shape but drastically reduce the polycount.
Here, I’m decimating the model to under five per cent and there is no noticeable difference in the decimated shape from the high-res (besides the colour).
To do this with Decimation Master, combine all your highres subtools into one mesh and preprocess the model before decimating it (see image 9).
10 SET UP LIGHTING
Download the latest version of Renderman from Pixar’s website, which is free for non-commercial use. Download an HDRI that works for your character. I like telling a subtle story with lighting, so I chose a desert environment for this scene.
Start placing some Renderman lights in the scene – create a Pxrdomelight and connect the HDRI you chose to it.
Create three other Pxrlights (either Rect or Disk) for a threepoint set-up, one more distant one (it’s going to make for less spread out shadows) to emulate the sun, one for the bounces and one for the rim light. This last one will serve for both the rim lighting and for subsurface scattering (SSS) as I’ll have SSS material on the character for the final render.
Start tweaking the lights one by one, rendering first with only the dome light, then the other ones in isolation, and finally combining them. Keep your resolution and sampling fairly low for this as you don’t want to wait too long for the renders. Use the Crop tool to isolate an interesting section of the render to make it quicker. This way you can finely tweak the lighting in the scene to complement the model.
11 MATERIALS
I use a Renderman SSS (Pxrlmsubsurface) material for the final render. That’s because I love the slight translucency in the surface and the shadow. The light keeps travelling past where it’s directly lit, and this effect is not coming from bounces from the HDRI, it’s actually inside the material.
As for the material settings, I use Overlay to add a bit of extra sheen and highlights to my character if the SSS gets too diffuse. Subsurface scattering is made up of three components: near, mid and far, based on the depth to which light
scatters through the volume. You can assign different colours to these and, based on how far the light has travelled within the material, they will give off that colour. I like a bluish tint for these, so I made them different tones of blue. The intensity the near mid and far colours contribute to the overall hue is defined by weight.
I recommend tuning the material first by isolating each of these three channels. Set weight to zero on the other two and see what it looks like, then start layering.
12 RENDERING
Use batch rendering so you can use the Denoise filter that will be applied by default. You’ll have two outputs, one labelled ‘_filtered’. Compare them to see the noise reduction provided in Renderman, without the need to increase a lot of the sampling (reducing the noise but increasing render time). THE RIGHT ORDER Primary forms, the big broad shapes, come before secondary forms (the break up of the big primitive shapes to get in more detailed forms), which come before tertiary forms (details). No amount of details will save a model where the primary forms suck. I set my Samples quite high for the final render. You can see from image 12a that I have it at 1024. The rest of the noise is handled by Denoise. Under Integrator, use Path Traces for opaque objects, (VCM is for transparent objects).
Finally, I add some Chromatic Aberration to the whole thing, giving a nice coloured rim to the model. Note, Chromatic Aberration adds a lot of noise to the render – it’s why my base sampling is jacked up high.
To activate Chromatic Aberration, click on the colour of the Transverse value and vary that by a miniscule degree (experimenting with it can give nice results with different broader values).
Place your Camera correctly, (test it with less expensive render settings first), hit Renderman >Batch-render, then go get a coffee (or three) while you wait for your work to come to life.